Asthma pathophysiology and evidence-based treatment of severe exacerbations.

PURPOSE: The pathogenesis of asthma and the treatment approach for acute exacerbations are described. The pharmacology, efficacy, safety, and cost of the beta2 agonist, albuterol, a racemic mixture of equal amounts of R- and S-enantiomers, and levalbuterol, the R-enantiomer, are compared.
SUMMARY: Asthma symptoms are the result of bronchial hyperresponsiveness, bronchospasm, and chronic airway inflammation. Short-acting, inhaled beta2 agonists; oxygen; intravenous fluids; and corticosteroids are the mainstays of treatment for acute exacerbations. The R-enantiomer of albuterol is responsible for bronchodilation. The S-enantiomer exhibits broncho-constricting activity in vitro, which may be mediated by muscarinic receptors and may be opposed by adding the anticholinergic agent ipratropium bromide. Levalbuterol improves pulmonary function to a greater extent than racemic albuterol and reduces the need for costly hospitalizations in patients with acute asthma exacerbations.
CONCLUSION: Levalbuterol is an alternative to racemic albuterol with the potential to improve patient outcomes and reduce costs in the treatment of acute asthma exacerbations.